Printing press and method



1962 c. o. SIEBKE 3,048,098

PRINTING PRESS AND METHOD Filed Jan. 12, 1960 INVENTOR Carl 0. SiebkeUnite States This invention relates to a printing press and method. Itrelates particularly to a method and means for improving the printingquality of a printing press in which ink is applied to the formaccompanied by the application of water which becomes admixed oremulsified with the ink, as in lithographic offset printing.

As is Well known to those skilled in the art, ink and water are appliedto the form or printing plate in lithographic offset printing, the inkand water forming an emulsion. The water is applied to keep the printingform or plate sufficiently wet in the non-printing areas so that theink, which has an oily base, will not be deposited in those areas. Thewater unavoidably forms an emulsion with the ink. Formation of theemulsion is not desired but is one of the necessary evils of theprocess. In lithographic printing the best results are obtained by usinga minimum amount of water. However, enough water must be kept in thenon-printing areas of the plate to prevent those areas from drying up;otherwise the plate will pick up ink and start printing. For uniformtone reproduction a constant ink-water balance or ratio should iremaintained.

While my invention is applicable to any printing process in which inkand water are used, its principal application is inthe lithographicoffset printing art, and for purposes of explanation and illustrationthe invention will be. described as embodied in a lithographic offsetprinting press and method.

In a lithographic offset printing press the so-called plate cylinder hasa printing form or plate applied to its surface which extends throughoutless than the full circumference of the cylinder. I herein use thegeneric term form which is to be understood to include any form forprinting in a press of the type to which the invention is applicable;the form in a lithographic offset printing press is commonly termed aprinting plate and is normally of flexible sheet metal such as Zinc oraluminum and-is applied to the surface of the cylinder and stretched andfastened in place thereon.

Since the printing plate or form extends throughout less than the fullcircumference of the cylinder there is a gap between the trailing andleading-edges of the form. As well known to those skilled in the art,the form in lithographic offset printing is hydrophylic. Ink is suppliedto the form through an inker having ink form rollers and which forpresent purposes may be deemed to be of conventional construction. Wateris also supplied to the form through a system of water supplying rollersand which for present purposes may be deemed to be of conventionalconstruction.

The system of water supplying rollers employed in presses of the typeabove referred to includes water form roller means which may, forexample, constitute two water form rollers adapted to directly engageand deliver water to the form or printing plate. Other rollers deliverwater to the water form rollers in conventional manner well known tothose skilled in the art. The rollers are driven constantly at constantspeed so water is delivered to the Water form rollers at a fixed(although adjust-able) rate of feed.

When the water form rollers are in engagement with the form they deliverwater thereto. When they are not in engagement with the form, i.e., whenthey are opposite the gap in the cylinder between the trailing andleading when water is being applied to the form. 7

3,048,098 Patented Aug. 7, 1962 edges of the form, they do not deliverwater to the form. But the rollers which deliver water to the water formrollers operate continuously and hence the water form rollers arereceiving a constant supply of water at all times regardless of whetheror not they are delivering water to the form. The result is that duringthe time when the water form rollers are opposite the gap between thetrailing and leading edges of the form the quantity of water carriedthereby builds up so that when they engage the form at the leadingportion thereof they deliver to that portion of the form a relativelygreat quantity of water and after that excess of water has beendelivered to the leading portion of the form the water form rollersdeliver a lesser quantity of water to the remainder of the form.

When the ink form rollers are traversing the gap between the trailingand leading edges of the form the ink on those rollers tends to losesome of its water content, increasing the intensity of the tone producedin printing. Regardless of how much water is on the form the ink appliedto the form will have a more intense tone for the first revolution ofthe ink form rollers. The water picked up from the form does not affectthe ink during the first revolution of the ink form rollers. It is,however, picked up by the ink form rollers and carried to the otherrollers of the inker such as distributing rollers and vibrating rollerswell known to those skilled in the art which cause the ink to be spreadin a film of uniform thickness. The ink is also thereby emulsified andwhen a form roller starts its second revolution on the form it depositsthereon the emulsified ink which is lighter in tone than unemulsifiedink.

' Therefore the ink form rollers on their first revolution deposit inkof a relatively intense tone while on the second revolution of the inkform rollers a lighter tone is produced because the form rollers havepicked up more water from the leading edge of the form and worked itinto the ink on the first revolution of the ink form rollers and depositit on the second revolution. While depositing ink on the form during thesecond revolution the ink form rollers also pick up water from the form.However, the amount of water thus picked up is less than that picked upon the first revolution of the ink form rollers on the form and so thetone of the ink applied to the form during the third revolution of theink form rollers is more dense than that of the ink applied during thesecond revolution but less dense than that of the ink applied during thefirst revolution. This is caused primarily by the fact that the waterform rollers store up water while passing through the gap and during thefirst revolution on the form deposit an excess of water. During theirsecond revolution they deposit less water than on the tfirst and duringtheir third revolution probably a little less than on the second.

The above described condition has existed since the invention oflithographic offset printing. Those skilled in the art have made manyattempts to avoid the unevenness of the tone of the printing but noentirely satisfactory solution to the problem has heretofore beendiscovered.

I provide a printing press and method obviating the disadvantages aboveexplained and insuring the supplying of water to the form at a fixedrate of feed. I provide a method of improving the printing quality of aprinting press in which ink is applied to the form and water is admixedwith the ink in the zone of application of ink to the form comprisingduring operation of the press supplying water at a fixed rate of feedfor admixture with the ink. Preferably the water is applied to the formfor admixture with the ink and I supply the water to the form at a fixedrate of feed at all times I preferably supply the water to the zone ofapplication thereof to the form at a fixed rate of feed and duringintervals while no portion of the form is at said zone remove water fromthe supply at the same rate as the form removes water from the supply toavoid accumulation of Water during such intervals so that at all timeswhen water is being applied to the form it is applied to the form at afixed rate of feed. The removal of the water from the supply during theintervals while no portion of the form is at the zone of application ofwater thereto is preferably accomplished by engaging the water supplywith a moving surface which removes water therefrom at the same rate asthe form removes water from the supply.

I further provide, in a printing press, a form cylinder, a form on thecylinder extending throughout less than the full circumference of thecylinder and means for supplying ink and water for application to theform, said means including means insuring supplying water forapplication to the form at a fixed rate of feed during operation of thepress. My press preferably comprises means for applying ink to the form,means for applying water to the form and means cooperating with themeans for applying water to the form insuring applying water to the format a fixed rate of feed during operation of the press. I preferablyprovide means operative during intervals while no portion of the form isin Water receiving relationship to the means for applying water to theform removing water from the means for applying water to the form at thesame rate as the form removes water therefrom when in water receivingrelationship therewith to obviate accumulation of water by the means forapplying water to the form during said intervals, which accumulationwould result in application of water to the form at a fluctuating rateof feed, thereby insuring application of water to the form at a fixedrate of feed during operation of the press.

I preferably provide a moving hydrophylic surface engaging the means forsupplying water to the form during intervals while no portion of theform is in water receiving relationship to the means for applying waterto the form removing water from the means for applying water to the format the same rate as the form removes water therefrom when in waterreceiving relationship therewith.

In my preferred structure I provide bridging means applied to thecylinder at the portion of the circumference thereof not covered by theform and having a hydrophylic surface of substantially the samecurvature as the form, so that the surfaces of the form and of thebridging means together constitute substantially a full cylindricalhydrophylic surface, said surface of the bridging means removing waterfrom the means for applying water to the form at the same rate as theform receives water therefrom when in water receiving relationshiptherewith. The means for applying water to the form preferably comprisewater form roller means, and water is supplied to the water form rollermeans at a fixed rate of feed during operation of the press.

Other details, objects and advantages of the invention will becomeapparent as the following description of a present preferred embodimentthereof and a present preferred method of practicing the same proceeds.

In the accompanying drawings I have shown a present preferred embodimentof the invention and have illustrated a present preferred method ofpracticing the same in which FIGURE 1 is a diagram showing the formcylinder and the means for applying ink and water to the form in alithographic offset press;

FIGURE 2 is a diagrammatic view to enlarged scale of the form cylinderhaving the bridging means of my invention applied thereto;

FIGURE 3 is a plan view of the under side of the bridging means;

FIGURE 4 is an end view of the bridging means; and

FIGURE 5 is a fragmentary cross-sectional View to enlarged scale of thebridging means, taken on the line VV of FIGURE 3.

Referring now more particularly to the drawings and in the firstinstance to FIGURE 1, the form or plate cylinder of a lithographicoffset press is designated by reference numeral 2. Ink is applied to thecylinder 2 by inking means designated generally by reference numeral 3and which may be conventional. The inking means 3 include four ink formrollers 4. Water is applied to the form by water applying meansdesignated generally by reference numeral 5. The water applying means 5include two water form rollers 6. Everything shown in FIGURE 1 may beconvention except the cylinder 2, and no attempt is made in the smallscale drawing constituting FIGURE 1 to illustrate the bridging means,which are illustrated in FIGURES 2-5.

Referring now to FIGURE 2, the cylinder 2 has a lithographic oifsetprinting plate 7 applied thereto in ocnventional manner. The printingplate 7 is a thin flexible sheet metal plate made, for example, of sheetaluminum which is clamped and stretched about the cylinder 2 by clampingand stretching means which may he conventional. The clamping andstretching means are duplicated at the two ends of the printing plate 7,such mechanism being, however, illustrated at only one end of theprinting plate and designated generally by reference numeral 8. Allstructure thus far described may be conventional and hence no detaileddescription of elements of the structure well known to those skilled inthe art is included.

The cylinder 2 rotates in the counte clockwise direction or in thedirection of the arrows 9* in FIGURES 1 and 2. The leading edge of theprinting plate 7 is at It and the trailing edge is at 11. The printingplate 7 is continuous along the surface of the cylinder 2 from theleading edge 10 to the trailing edge 11. However, from the trailing edge11 to the leading edge 10 at the right-hand side of FIGURE 2 there is agap. In conventional lithographic oifset presses as provided prior tothe present invention the ink form rollers and the water form rollersmade no contact with any means for removing ink or wa'-- ter therefromwhile traversing the gap 1110-. As a result, since the water supplyingrollers behind the water form rollers 6 operate continuously at constantspeed water was delivered to the water form rollers 6 at a fixed rate offeed resulting in a build-up of Water on the water form rollers 6 whilethey traversed the gap I l-10 with the undesirable results aboveexplained.

I provide bridging means designated generally by reference numeral 12which I apply to the cylinder 2 to bridge the gap 11-10. The bridgingmeans 12 may be of any suitable material such as steel or aluminum andmay comprise a plate-like outer portion 13 having a cylindrically curvedouter surface whose curvature is the same as that of the cylindricalsurface of the cylinder 2. The bridging means 12 are applied to thecylinder 2 so that the surface 13 thereof forms with the portion of thesurface of the cylinder 2 covered by the printing plate 7 substantiallya full cylinder. Small discontinuities 14 exist between the ends of thebridging means 12 and the leading and trailing ends 10 and 11 of theplate 7, such discontinuities being exaggerated in FIGURE 2. Actuallythey are so small that they are negligible in operation of the press.

The bridging means 12 are provided with drilled holes 15 through whichscrews 16 are applied threading into internally threaded bores *17 inthe cylinder to hold the bridging means in place on the cylinder.

The outer cylindrical surface of the bridging means is hydrophylic as isthe outer cylindrical surface of the printing plate 7. The outercylindrical surface of the bridging means may be made hydrophylic invarious ways known to those skilled in the art, as, for example, byslightly roughening the surface and coating it with gum arabic.

In operation of the press printing plate 7 and the bridging means 12considered collectively are engaged substantially continuously by thewater form rollers 6 which deliver water thereto at a fixed rate offeed. Thus the provision of the bridging means 12 obviates the formerbuildup of excess water on the water for-m rollers when traversing thegap between the trailing and leading ends of the printing plate. Theresult is the maintaining of a uniform proportion of water to ink andconsequently a uniform tone in the printed work.

While I have shown and described a present preferred embodiment of theinvention and a present preferred method of practicing the same it is tobe distinctly understood that the invention is not limited thereto butmay be otherwise variously embodied and practiced Within the scope ofthe following claims.

I claim:

1. In a printing press, a form cylinder, a form on the cylinderextending throughout less than the full circumference of the cylinder,means including roller means engaging the form for applying ink to theform, means for applying water to the form and means cooperating withthe means for applying water to the form insuring applying water to theform by such roller means at a fixed rate of speed during operation ofthe press.

2. In a printing press a form cylinder, a form on the cylinder extendingthroughout less than the full circumference of the cylinder, means forapplying ink to the form, means for applying water to the form andmeans, operative during intervals while no portion of the form is inwater receiving relationship to the means for applying water to theform, removing water from the means for applying water to the form atthe same rate as the form removes water therefrom when in waterreceiving relationship therewith to obviate accumulation of water by themeans for applying water to the form during said intervals, whichaccumulation would result in application 'of water to the form at afluctuating rate of feed, thereby insuring application of water to theform at a fixed rate of feed during operation of the press.

3. In a printing press, a form cylinder, a form on the cylinderextending throughout less than the full circumference of the cylinder,means for applying ink to the form, means for applying water to the formand a moving hydrophylic surface engaging the means for applying waterto the form during intervals while no portion of the form is in waterreceiving relationship to the means for applying water to the formremoving water from the means for applying water to the form at the samerate as the form removes water therefrom when in water receivingrelationship therewith to obviate accumulation of water by the means forapplying water to the form during said intervals, which accumulationwould result in application of water to the form at a fluctuating rateof feed, thereby insuring application of Water to the form at a fixedrate of feed during operation of the press.

4. In a printing press, a form cylinder, a form on the cylinderextending throughout less than the full circumference of the cylinder,means for applying ink to the form, means for applying water to the formand bridging means applied to the cylinder at the portion of thecircumference thereof not covered by the form and having a hydrophylicsurface of substantially the same curvature as the form, so that thesurfaces of the form and of the bridging means together constitutesubstantially a full cylindrical hydrophylic surface, said surface ofthe bridging means removing water from the means for applying water tothe form at the same rate as the form removes water therefrom when inwater receiving relationship therewith to obviate accumulation of waterby the means for applying water to the form during intervals while noportion of the form is in water receiving relationship to the means forapplying water to the form, which accumulation would result inapplication of water to the form at a fluctuating rate of feed, therebyinsuring application of water to the form at a fixed rate of feed duringoperation of the press.

' 5. In a printing press, a form cylinder, a form on the cylinderextending throughout less than the full circumference of the cylinder,means for applying ink to the form, water from roller means for applyingwater to the form, means for supplying water to the water form rollermeans at a fixed rate of feed during operation of the press and meansoperative during intervals while no portion of the form is in waterreceiving relationship to the water form roller means removing waterfrom the water form roller means at the same rate as the form removeswater therefrom when in water receiving relationship therewith toobviate accumulation of water on the water form roller means during saidintervals, which accumulation would result in application of water tothe form at a fluctuating rate of feed, thereby insuring application ofwater to the form at a fixed rate of feed during operation of the press.

6. In a printing press, a form cylinder, a form on the cylinderextending throughout less than the full circumference of the cylinder,means for applying ink to the form, water form roller means for applyingwater to the form, means for supplying water to the water form rollermeans at a fixed rate of feed during operation of the press and bridgingmeans applied to the cylinder at the portion of the circumferencethereof not covered by the form and having a hydrophylic surface ofsubstantially the same curvature as the form, so that the surfaces ofthe form and of the bridging means together constitute substantially afull cylindrical hydrophylic surface, said surface of the bridging meansremoving water from the water form roller means at the same rate as theform removes Water therefrom when in water receiving relationshiptherewith to obviate accumulation of water on the water form rollermeans during intervals while no portion of the form is in waterreceiving relationship to the water form roller means, whichaccumulationwould result in application of water to the form at afluctuating rate of feed, thereby insuring application of water to theform at a fixed rate of feed during operation of the press.

7. A method of improving the printing quality of a printing press of thetype having a form cylinder with a form thereon extending throughoutless than the full circumference of the cylinder and in which ink isapplied to the form and water is applied to the form by rollers engagingthe form for admixture with the ink comprising at all times when wateris being applied to the form applying the water to the form by suchrollers at a fixed rate of feed.

8. A method of improving the printing quality of a printing press of thetype having a form cylinder with a form thereon extending throughoutless than the full circumference of the cylinder and in which ink isapplied to the form and water is applied to the form for admixture withthe ink comprising supplying the water to the zone of applicationthereof to the form at a fixed rate of feed and during intervals whileno portion of the form is at said zone removing water from the supply atthe same rate as the form removes water from the supply to avoidaccumulation of water during such intervals so that at all times whenwater is being applied to the form it is applied to the form ata fixedrate of feed.

9. A method of improving the printing quality of a printing press of thetype having a form cylinder with a form thereon extending throughoutless than the full circumference of the cylinder and in which ink isapplied to the form and water is applied to the form for admixture withthe ink comprising supplying the Water to the zone of applicationthereof to the form at a fixed rate of feed and during intervals whileno portion of the form is at said zone engagingthe water supply with amoving surface which removes water from the supply at the same rate asthe form removes Water from the supply to avoid accumulation of Waterduring such iu- 664,965 Morriss Jan. 1, 1901 Wolff Sept. 19, 1933Schultz May 15, 1934 Gcedike Mar. 8, 1938 Martin Aug. 30, 1955 Koch .May7, 1957 Bc-rchers Aug. 23, 1960 UNITED STATES PATENT OFFICE CERTIFICATEOF CORRECTION Patent No. 3,348,098 August. 7, 1962 Carl 0. Siebke It ishereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 4, lines 20 and 21, conventional column 5, line 19, after"cylinder," insert means for applying ink to the form, line 20, for"ink" read water lines 20 and 21, strike out means for applying water tothe form same column, line 24, for "speed" read feed Signed and sealedthis 20th day of November 1962.

for "conventional" read (SEAL) Attest:

DAVID L. LADD ERNEST W. SWIDER Commissioner of Patents Attesting Officer

